<html>
<head>
    <style>
        p {
            color: blue;
            opacity: 0;
            animation: keyframeName 3s infinite;
        }
        @keyframes keyframeName {
            0%, 100% {
                opacity: 0;
            }
            50% {
                opacity: 1;
            }
        }
    </style>
</head>
<body>
    <p>hi</p>
</body>
</html>
